﻿2G4 



On the Velocity of Sound in Air §c. 

 §7. 



After my experiments were finished I had some doubt as 

 to whether the vibration-frequency of e t was exactly 256. I 

 decided the point by means of an electric registration method. 

 A small, thin, pointed piece of platinum-plate was attached 

 to the end of one of the prongs of the fork, and the vibration- 

 curves were traced on a metal cylinder coated with blackened 

 paper. A weak induction-current, with mercury contact with 

 the seconds-pendulum of a clock of known daily error, was 

 generated and conducted by the platinum point to the 

 blackened paper. The number of waves between the marks 

 of the sparks, taken two and two, gave the double vibration- 

 frequency of the fork. As a result I found that e l made 

 256*23 vibrations per second. This necessitated small cor- 

 rections in my results, which are shown below. 





Velocity 



of Sound. 







Uncorrected. Corrected. 



Eegnault *. 



Air 



330-582 m. 



257 '03 in. 



1236 5 m. 



330-88 m. 



257-26 m. 



1237-6 m. 



3307 in. 

 259-57 m. 

 1200-77 & 1106-67 m. i 

 178-8 m.t 



Carbonic Acid ... 

 Hydrogen 



Ether Vapour ... 



175-77 m. 



17593 m. 



Corresponding corrected Ratios of the Specific Heats. 





Low. 



Eontgen %. 



P. A. Muller §. 



Air 



1-3968 

 1-2914 

 1-3604 

 10244 



1-4053 

 1-3052 

 1-3852 



14062 

 1-2653 



1-02S8 (at 22°) 

 1094 t 



Carbonic Acid ... 

 Hydrogen 



Ether Vapour ... 



* Mem. de Vlnst. xxxvii. p. 133; Compt. Rend. lxvi. p. 219 (18G8). 

 t Jaeger, Wied. Ann. xxxvi. p. 209 (1880). 

 | Posrg. Ann. cxlviii. p. 608 (1873). 

 § Wied. Ann. xviii. p. 11 G (1880). 



